Reversible Transformation of a μ3‑η3‑C3 Ring into μ3‑η2‑Ethyne and μ‑Vinylidene Ligands at a Triruthenium Site upon Deprotonation and Protonation

A μ-vinylidene-μ3-η2-ethyne complex, [(Cp*Ru)3(μ3-CH)­(μ-CCH2)­(μ3-η2-HCCH)] (4; Cp* = η5-C5Me5), was synthesized by the reaction of [(Cp*Ru)3(μ3-CH)­(μ3-η3-C3MeH2−)]+ (3a) with KN­(SiMe3)2 via deprotonation of the methyl group on the μ3-η3-C3 ring followed by C–C bond cleavage. The reaction of 4 with an electrophile resulted in the reconstruction of the μ3-η3-C3 ring via the coupling of two hydrocarbyl moieties at the Ru3 site. The reaction of 4 with iodomethane resulted in C–C bond formation at the β-carbon atom of the vinylidene ligand, leading to the formation of [(Cp*Ru)3(μ3-CH)­(μ3-η3-C3EtH2−)]+ (3c). These unprecedented skeletal rearrangements arose from the unique electronic properties of the μ3-η3-C3 ring, which comprised three unsaturated μ-carbenes.